Electronic – Track loader actuators: Provide reverse capability for two DC motors, on board snow blower attachment

dc motorreverse-polarityswitches

enter image description hereI bought a 7 ft wide John Deere snowblower and want to use it on an ASV track loader. The two companies use different strategies for running electrical units on attachments. This requires wiring up special electrical devices on the attachment to run it using my Joystick in the ASV Loader. The pigtail leading outside the loader to run the two DC motors has:
4 wires each of which is energizable via a dedicated, momentary button on the joystick, and
2 ground wires.

The two 12 volt DC motors operate the snowblower accessories to 1) rotate the snorkel exhaust tube either CW or CCW to redirect snow Left or Right of machine and 2) move a deflector plate up or down on the exhaust exit port . This physical movement is done by reversing the polarity of the two motors on a momentary basis– 2 or 3 seconds each time.

Wiring available on the input side of the snowblower is simply the two wires from each DC motor, no grounds– 4 wires total.

After discussion with ASV technician I concluded the only way to accomplish this is to use two relays for each motor. (To me, this sounds excessive, as an accomplished rookie at electrical work.) I generated a crude relay diagram to operate just one motor, attached.

To assist me it would be most helpful to:

— Suggest ways to simplify: a double coil relay?? Is there such a thing?

— Suggest a better way altogether.enter image description here

— Actual model numbers or specific types and brands of relays (plan on sealing in a small box and mounting on the attachment, probably see a lot of weather)

Thanks!

Best Answer

You are on the right track (no pun intended) with two double-pole-single-throw relays, but the wiring is not optimal. Your sketch feeds the motor current through the joystick buttons; when you release a button there will probably be an arc that eventually damages the switch contact.

Instead, keep the relay coil/button circuits separate from the relay contact/motor circuits.

  1. Hot feed C3 -> Joystick button D -> coil of C3 -> ground.
  2. Hot feed C2 -> Joystick button C -> coil of C2 -> ground.
  3. Hot feed C3 -> lower contact of relay C3 -> M1 brown.
  4. Hot feed C3 -> upper contact of relay C2 -> M1 green.
  5. Ground -> upper contact of relay C3 -> M1 green.
  6. Ground -> lower contact of relay C2 -> M1 brown.

Only use this if the joystick construction ensures button C and D are never pressed at the same time. If that happened, both relays operate at once, shorting out the battery and hopefully just blowing a fuse but possibly burning up wires.

With additional information (from OP's comment) we find there are already relays in the track loader, operated from each button. In this case, first check to see if the track-loader's outputs are grounded when inactivated. That could be the case, because it would help provide braking for electric motors when the joystick is release. If so, just connect the output of C to motor brown, output of D to motor green and you're done!

If the relays are only SPST, then it should be a simple matter to just replace these relays with SPDT units of similar size and configuration. Wire them with the COM contact as the output, the NC to ground, and the NO to fused hot. Now, as above, just connect one relay's output to motor Brown wire, the other relay's output to motor Green. Done!

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